In recent years, a lithium-ion capacitor that combines the principles of a lithium-ion secondary battery and an electrical double layer capacitor has attracted attention as an electric storage device that may be used for applications that require high energy density and high output characteristics. The lithium-ion capacitor is configured so that the energy density can be significantly increased by causing the anode to occlude (store) and support lithium ions (hereinafter may be referred to as “doping”) using an electrochemical method or the like to lower the anode potential.
For example, JP-A-2007-67105 discloses technology that disposes a lithium foil (lithium ion source) in a wound element formed by disposing a separator between a cathode and an anode, and winding the cathode, the anode, and the separator, and dopes lithium ions into the anode via electrochemical contact between the anode and the lithium foil.